Method of controlling the braking device of a trailer and braking device operating according to this method

ABSTRACT

The invention relates to a method for controlling a braking device equipping a trailer vehicle, connected by a coupling device to a towing vehicle being itself equipped with a braking device,  
     according to which method, when braking the towing vehicle:  
     the intensity of the force induced in the coupling device is measured, at least at a given moment, then  
     the intensity of the induced force measured at the given moment under consideration is compared with a target value determined beforehand and, when the difference between the intensity of the measured induced force and the said target value deviates from a predetermined tolerated threshold, the actuation of braking elements of the trailer vehicle are ordered to influence the braking of the said trailer vehicle, and  
     the aforementioned steps are repeated of measuring, comparing and ordering of the braking until the difference between the intensity of the measured induced force and the target value is less than the predetermined tolerated threshold,  
     wherein  
     the moment starting from which the towing vehicle and the trailer vehicle are about to roll is detected and monitored, then, starting from that moment  
     the intensity of the force induced in the coupling device is measured and,  
     for a period of measurement of predetermined duration, the average value is calculated of the intensity of the induced force and this value is stored,  
     with a view to ordering the actuation of the braking elements of the trailer vehicle, taken as the target value is the average value of the intensity of the induced force which has been calculated in the period of measurement preceding the moment chosen to order the said braking. This invention also concerns a braking device operating according to said method.

[0001] The invention relates to a method of controlling a braking deviceequipping a trailer vehicle, this vehicle being connected through acoupling device to another vehicle, referred to as the towing vehicle.The invention likewise relates to a braking device for a trailervehicle, which device comprises a controlling apparatus which implementsthe aforesaid method. The invention also relates to trailer vehiclesequipped with said braking device.

[0002] The invention concerns more particularly, but not exclusively,the domain of non-dedicated trailers, i.e. trailer vehicles which arecoupled to a towing vehicle of light-weight type. Meant by light-weightvehicle are vehicles whose total loaded weight does not exceed threethousand five hundred kilograms.

[0003] A braking device for a vehicle comprises in general brakingelements each connected to a wheel of the vehicle as well as a meansallowing the simultaneous actuation of these braking elements when thedriver of the towing vehicle wishes to brake.

[0004] Known in this field is the actuation of the braking elements forthe wheels of the trailer vehicles by means of devices of the typereferred to as “overrunning brakes,” i.e. with devices which aresensitive to the deceleration of the towing vehicle, consequently to theoperation of the braking device of said towing vehicle. These actuationapparatuses are placed in the device for coupling the vehicles, and areconceived so as to exploit a relative displacement of said trailervehicle toward said towing vehicle to activate the braking elements ofthe trailer vehicle.

[0005] These apparatuses are preferably very simple in construction andessentially comprise, for example, a mechanical control activating thebraking elements for the wheels of the trailer vehicle via cables androds. Speaking against these overrunning type braking controlapparatuses, however, is, on the one hand, ill-timed or inopportuneoperation when these vehicles descend a steep slope and, on the otherhand, not braking when the vehicles are backing up on a descendingslope.

[0006] To solve this, the preferred solution consists of putting thebraking elements of the trailer vehicle under the influence of theactuation element, such as the brake pedal, which is used to control thebraking device of the towing vehicle. This requires, in general,significant adaptations made in the towing vehicle in order to makepossible proportional and simultaneous control of the braking devices ofthe two vehicles, the trailer vehicle and the towing vehicle. Thisproportional and simultaneous control of the braking devices of thetowing and trailer vehicles does not permit dealing with cases ofexcessive braking or of insufficient braking of the trailer vehicle,however.

[0007] Known, as a way of overcoming this drawback, is to influence theoperation of the braking device of the trailer vehicle as a function ofthe intensity of the force induced in the coupling device during thebraking. To this end, the part of the coupling device equipping thetowing vehicle is provided with a force detector and said towing vehicleitself is equipped with a controlling apparatus which, during braking ofthe towing vehicle:

[0008] measures the intensity of the force induced in the couplingdevice, at least at a given instant, then

[0009] compares the measured intensity of the induced force at the giveninstant under consideration with a target value determined beforehandand, when the difference between the measured intensity of the inducedforce and said target value is greater than a predetermined toleratedthreshold, commands the actuation of the braking elements of the trailervehicle to influence the braking of said trailer vehicle, and

[0010] repeats the aforementioned steps of measuring, comparing andcommanding the braking until the difference between the measuredintensity of the induced force and the target value are less than thepredetermined tolerated threshold.

[0011] A controlling apparatus operating according to this known methodhas its advantages, but its operation is optimal only under veryspecific conditions.

[0012] In fact, since the target value is fixed, the method does notpermit taking into account the declivity of the route or the use of aretarder device such as an induced current brake. Resulting therefrom isa non-harmonious progression of braking between the towing vehicle andthe trailer vehicle.

[0013] The functioning of the aforementioned apparatus is no longerprovided for when managing an act of braking actuated when the coupledvehicles are moving backwards down a slope.

[0014] One result which the invention aims to obtain is, precisely, acontrol method which allows the weight of the trailer vehicle to betaken into account and which gauges itself automatically with a view toensuring a better performance of said trailer vehicle and of the towingvehicle, and this when these vehicles are rolling freely as well as whenthey are braking.

[0015] Another result which the invention aims to obtain is a controlmethod which allows actuation of the braking in forward drive or inreverse drive of the vehicles.

[0016] Still another result which the invention aims to obtain is acontrol method which allows the assembly of functional means necessaryto control the braking of the trailer vehicle to be centralized on saidtrailer vehicle.

[0017] Other results of the invention are mentioned in the following.

[0018] The invention has as its object a control method of theaforementioned type, this method being characterized in particular inthat:

[0019] through monitoring, the instant starting from which the towingvehicle and the trailer vehicle are about to roll is detected, then,starting from that instant

[0020] at least in an intermittent way, the intensity of the forceinduced in the coupling device is measured and,

[0021] for a period of measurement of predetermined duration, theaverage value is calculated of the intensity of the induced force andthis average value is stored,

[0022] after completion of the storage of an average value, the stepsare repeated of measuring, calculating a new average value then ofstoring this new average value, replacing the average value previouslystored,

[0023] with a view to initiating the actuation of the braking elementsof the trailer vehicle at any chosen instant after the calculation of anaverage value, taken as the target value is the average value of theintensity of the induced force which has been calculated in the periodof measurement preceding the instant chosen to initiate said braking.

[0024] The invention likewise has as an object a braking device for atrailer vehicle, which device comprises a controlling apparatusimplementing the aforementioned method.

[0025] The invention also has as an object trailer vehicles equippedwith the mentioned braking device.

[0026] The invention will be better understood from reading thefollowing description, given by way of non-limiting example andillustrated by the attached drawing in which

[0027]FIG. 1 shows diagrammatically and from above a group of twovehicles 1, 2 connected through a coupling device 3, the trailer vehicle1 being provided with a braking device 7 that implements the controlmethod according to the invention, and

[0028]FIG. 2 shows a table containing two graphs G1 and G2 illustrating,in a time dependency diagram, commands E1, E2, F1, F2, F3 given to thebraking device of the trailer vehicle as a function of the direction ofstress of the coupling device (graph G1 for the direction ofcompression, graph G2 for the direction of traction) and the differenceD noted between the measured intensity of the induced force and saidtarget value 10 (see also FIG. 1).

[0029] Referring to the FIG. 1, one sees a group of two vehicles 1, 2,and, to be more exact, a first vehicle 1 provided with wheels 4,referred to as the trailer vehicle 1, which is connected through acoupling device 3 to a second vehicle 2, likewise provided with wheels5, referred to as the towing vehicle 2.

[0030] The expressions rolling trailer vehicle 1 or rolling towingvehicle 2 are also used further below.

[0031] Likewise designated by trailer vehicle 1 is a vehicle of one ormore central axles, as well as a vehicle with a plurality of axles ofwhich at least one allows itself to be driven, or even a vehicle of thesemi-trailer type with one or more axles.

[0032] Designated by towing vehicle 2 is a vehicle equipped with a motoris means 6 for driving its wheels 5.

[0033] Designated by coupling device 3 is any device 3 permitting anarticulated connection between the towing vehicle 3 and the trailervehicle 1.

[0034] Although it has not been shown in the drawing, the vehicles areintended to roll on any surface foreseen for that purpose.

[0035] As has been indicated symbolically, each of the vehicles 1, 2 isequipped with a device 7, 8 for braking the rotation of its wheels 4, 5,each device 7, 8 comprising braking elements 71, 81 of said wheels 4, 5and a circuit 72, 82 for actuation of these elements 71, 81 with a viewto actuating the braking of the vehicle 1, 2 at a chosen moment.

[0036] The braking devices can be of any type, for example mechanical,hydraulic, pneumatic, electric.

[0037] As has been shown, the braking device 8 of the towing vehicle 2also comprises an element 83 for actuation of the braking devices 81 bya person (not shown).

[0038] Although it is not obvious from the drawing, the coupling device3 is equipped with a sensor 30 disposed for measuring the intensity ofthe force induced in said coupling device 3, in particular when braking,and for delivering information relating to the value of the inducedforce.

[0039] Designated by the expression “force induced in the couplingdevice” is a force which is oriented substantially axially to saidcoupling device. For example, when the coupling device 3 comprises adrawbar, the induced force is directed substantially axially to thisdrawbar.

[0040] The braking device 7 of the trailer vehicle 1 comprises acontrolling apparatus 73 which uses the information emitted by thesensor 30 to control the actuation of the braking elements 71 in such away that, during said braking, the force induced in the coupling device3 remains less than a predetermined target value 10.

[0041] To be precise, the controlling apparatus 73 situated in thebraking device 7 of the trailer vehicle 1 implements a control methodaccording to which, during braking of the towing vehicle:

[0042] the intensity of the force induced in the coupling device 3 ismeasured, at least at a given instant, then

[0043] the measured intensity of the induced force at the given instantunder consideration is compared with a target value 10 determinedbeforehand and, when the difference between the measured intensity ofthe induced force and said target value 10 deviates from a predeterminedtolerated threshold, the actuation of braking elements 71 of the trailervehicle 1 is initiated to influence the braking of said trailer vehicle1, and

[0044] the aforementioned steps are repeated of measuring, comparing,and initiating the braking until the difference between the measuredintensity of the induced force and the target value 10 is less than thepredetermined tolerated threshold.

[0045] According to the invention, this method is noteworthy in that:

[0046] through monitoring, the instant starting from which the towingvehicle 2 and the trailer vehicle 1 are about to roll is detected, then,starting from that instant

[0047] at least in an intermittent way, the intensity of the forceinduced in the coupling device 3 is measured and,

[0048] for a period of measurement of predetermined duration, theaverage value is calculated of the intensity of the induced force andthis average value is stored,

[0049] after completion of the storage of an average value, the stepsare repeated of measuring, calculating a new average value then ofstoring this new average value, replacing the average value previouslystored,

[0050] with a view to initiating the actuation of the braking elements71 of the trailer vehicle 1 at any chosen instant after the calculationof an average value, taken as the target value 10 is the average valueof the intensity of the induced force which has been calculated in theperiod of measurement preceding the instant chosen to initiate saidbraking.

[0051] In a way also noteworthy, to initiate the actuation of thebraking elements 71 of the trailer vehicle 1 at any chosen instant afterthe calculation of an average value:

[0052] the production is monitored on the towing vehicle 2 of a signal,referred to as the operational signal, which indicates the actuation ofits braking device and thus the instant chosen to initiate the brakingof the vehicles, and

[0053] when the force induced in the coupling device 3 by the trailervehicle 1 deviates with respect to the tolerated threshold predeterminedwith respect to the target value 10, the actuation of the brakingelements 71 of the trailer vehicle 1 is initiated, with a view tocorrecting the intensity of said induced force, only if the signal 11 ofoperation of the braking device 8 of the towing vehicle 2 has beendetected beforehand.

[0054] In a noteworthy way, the production is monitored on the towingvehicle 2 of a signal 11 which, referred to as the operational signal,is an electrical signal 11 produced to activate the operation ofluminous signals intended to indicate the use of the brakes of saidtowing vehicle 2, and thus indicate the actuation of the braking device8 of this vehicle.

[0055] On the one hand, when the actuation of the braking is detected,the process of calculation of an average value for the force induced inthe coupling device 3 is interrupted, and the development of the forceinduced in the coupling device 3 is monitored and, on the other hand,when the braking has been achieved, the process of calculation of theaverage value for the force induced in the coupling device 3 is resumed.

[0056] These first technical features of the method make it possible toensure the optimal braking of the trailer vehicle, regardless of itsload.

[0057] In a noteworthy way, the intensity of the force induced in thecoupling device 3 is measured with a predetermined frequency ofmeasurement so as to achieve a substantially continuous monitoring ofthe intensity of the force induced in said coupling device 3.

[0058] The frequency of measurement as well as moreover the number ofmeasurements necessary to be able to establish an average value can bedetermined by trials according to the materials used.

[0059] In a way likewise noteworthy:

[0060] the intensity of the force induced in the coupling device 3 bythe trailer vehicle 1 is measured in the two possible directions ofstress of this coupling device 3, i.e. in traction and in compression,and

[0061] a piece of information relating to the direction of the forceconsidered is linked to the measured intensity, and

[0062] used in addition to the measured value of the induced force bothin calculating an average value and in monitoring the development of theforce during an act of braking is the information relating to thedirection of the induced force so as to actuate the braking regardlessof the direction of displacement of the vehicles 1, 2 connected throughthe coupling device 3 and regardless of the inclination of the surfaceon which said vehicles are moving.

[0063] In a noteworthy way:

[0064] when the force induced in the coupling device 3 is detected inthe direction of compression of said coupling device 3,

[0065] if, in absolute value, the difference D between the measuredintensity of the induced force and said target value 10 is greater thana first predetermined threshold value A, then the braking is increasedEl, whereas

[0066] if, in absolute value, the difference D between the measuredintensity of the induced force and said target value 10 is less thansaid first predetermined threshold value A, then the braking E2 ismaintained in the same state,

[0067] when the force induced in the coupling device 3 is detected inthe direction of traction of said coupling device 3,

[0068] if, in absolute value, the difference D between the measuredintensity of the induced force and said target value 10 is less than asecond predetermined threshold value B, then the braking is decreasedF1,

[0069] if, in absolute value, the difference D between the measuredintensity of the induced force and said target value 10 is greater thansaid second predetermined threshold value B, but less than a thirdpredetermined threshold value C, then the braking is maintained in thesame state F2,

[0070] if, in absolute value, the difference D between the measuredintensity of the induced force and said target value 10 is greater thansaid third predetermined threshold value C, then the braking isincreased F3.

[0071] As already mentioned, FIG. 2 consists of a table containing twographs G1 and G2 illustrating in a time dependency diagram commands (E1,E2, F1, F2, F3) given to the braking device of the trailer vehicle,depending upon the direction of stress of the coupling device (graph G1for the direction of compression, graph G2 for the direction oftraction), and the difference D noted between the measured intensity ofthe induced force and said target value 10. In the graphs G1 and G2, thedifference D between the measured intensity of the induced force and thetarget value can, in absolute value, develop between the value zero (O)and a value greater than zero. In the graph G1, a line parallel to thetime axis T represents a first threshold value, marked A. In the graphG2, there are two lines parallel to the time axis T, one, marked B,representing a second threshold value and the other, marked C,representing a third threshold value.

[0072] The expressions “the braking is increased,” “the braking ismaintained in the same state,” and “the braking is decreased” signify,for example, that the pressure is increased of a hydraulic fluid forcontrol of the braking elements, that this pressure is maintained, thatthis pressure is reduced, respectively.

[0073] The method according to the invention allows a dynamic adaptationof the target value, i.e. the reference value owing to the fact thatthis value is calculated continuously.

[0074] The method according to the invention permits taking into accountthe situation of the vehicles (moving forward or backing up on a levelor inclined surface) which makes possible a braking adapted to saidsituation.

[0075] With the methods using a fixed target value, the differencebetween the target value and the intensity value measured at the momentof an act of braking, does not reflect the reality of the situation andthe braking of the trailer vehicle is not optimal.

[0076] The aforementioned technical features of the method according tothe invention make it possible to ensure:

[0077] the braking of the trailer vehicle 1 when the towing 2 andtrailer 1 vehicles must come to a stop when climbing or must be able toback up, in a controlled way, on a declivity which they have previouslyascended,

[0078] the absence of braking when the towing 2 and trailer 1 vehiclesback up on a declivity which they have previously descended, thusavoiding the conventional brake release systems during such a maneuver.

[0079] In keeping with the invention, to detect the instant starting atwhich the towing vehicle 2 and the trailer vehicle 1 are about to roll,the switching on of voltage to a motor means element 6 of the towingvehicle 2 is monitored. For example, monitored is the switching on ofvoltage resulting from maneuvering an ignition key for an electricignition contact (not shown) on the towing vehicle 2.

[0080] Such a signal of switching on voltage is provided conventionallyon an electrical connection part (not shown) situated at the rear of atowing vehicle equipped with a coupling device. Such a connecting partmakes it possible to transmit to the trailer vehicle differentelectrical signals, such as control signals for luminous indicators ofchange of direction, control signals for luminous position indicators,control signals for luminous braking indicators, an electrical supplycurrent for a device situated on the trailer vehicle. Such a part iswidely known, and it is a question of a thirteen pole connector ofstandardized type known under the reference ISO 11446. The towingvehicle 2 has such a part of female type, and the trailer vehicle 1 thushas a male-type part.

[0081] Preferably, but not obligatorily, for control of the brakingdevice 7 of the trailer vehicle 1, an indication is obtained at thelevel of each wheel 4 of the trailer vehicle 1 relating to the rotationof that wheel 4, and the indications about the rotation of each of saidwheels 4 of the trailer vehicle 1 are taken into account so as toprevent their blockage in braking phase.

[0082] In a noteworthy way, a switching off of voltage to a motor meanselement 6 of the towing vehicle 2 is monitored and when such a switchingoff of voltage is detected, the braking device 3 of the trailer vehicle1 is actuated so as to stop said trailer vehicle 1.

[0083] These technical features make it possible to ensure the stoppingof the trailer vehicle in the event of failure of the coupling device 3,for instance in the case of breakage.

[0084] The braking device 7 for implementation of the method accordingto the invention is noteworthy in that the control circuit 72 for itsbraking elements 71 comprises at least one controlling apparatus 73ensuring the following operations:

[0085] to monitor and detect the instant starting at which the towingvehicle 2 and the trailer vehicle 1 are about to roll, and starting atthat instant,

[0086] at least intermittently, to measure the intensity of the forceinduced in the coupling device 3, and

[0087] for a measuring period of predetermined duration, to calculatethe average value of the intensity of the induced force and to storethat average value,

[0088] upon completion of storing an average value, to repeat the stepsof measuring, of calculating a new average value, then of storing thisnew average value replacing the average value previously stored,

[0089] with a view to initiating the actuation of the braking elements71 of the trailer vehicle 1 at any chosen instant after calculation ofan average value, to take as a target value 10 the average value of theintensity of the induced force which has been calculated in themeasurement period preceding the instant chosen for actuating saidbraking.

[0090] In a noteworthy way, furthermore, to command the actuation of thebraking elements 71 of the trailer vehicle 1 at any chosen instantbefore calculation of an average value, the controlling apparatus 73 isdesigned to ensure the following operations:

[0091] to monitor and detect the production of a signal 11 of operationof an actuation element 83 for a braking device 8 of a towing vehicle 2,this signal making known the instant chosen for actuation of thebraking,

[0092] when such an operational signal has been detected, to determinewhether the intensity of the force induced in the coupling device 3 bythe trailer vehicle 1 deviates from a tolerated threshold predeterminedwith respect to a previously stored target value 10,

[0093] to initiate the actuation of the braking elements 71 of thetrailer vehicle 1 in the case where the intensity of the force inducedin the coupling device 3 by the trailer vehicle 1 deviates from atolerated threshold predetermined with respect to the target value 10.

[0094] Also in a noteworthy way, the controlling apparatus 73 isdesigned to monitor the production on the towing vehicle 2 of a signal11 which, referred to as the operational signal, is an electrical signal11 produced to activate the operation of luminous signals intended toindicate the use of the brakes of said towing vehicle 2, and thus makeknown the actuation of the braking device 8 of this vehicle.

[0095] In a manner also noteworthy, the controlling apparatus 73 isdesigned to interrupt, when the actuation of the braking is detected,the process of calculation of an average value for the force induced inthe coupling device 3 and to monitor the development of the forceinduced in said coupling device 3, and, when the braking has beenachieved, to resume the process of calculation of the average value forthe force induced in the coupling device 3.

[0096] Also in a noteworthy way, the controlling apparatus 73 isdesigned to measure the intensity of the force induced in the couplingdevice 3 with a predetermined frequency of measurement so as to achievea substantially continuous monitoring of the intensity of the forceinduced in said coupling device 3.

[0097] Also in a noteworthy way, the controlling apparatus 73 isdesigned:

[0098] to measure the intensity of the force induced in the couplingdevice 3 by the trailer vehicle 1 in the two possible directions ofstress of this coupling device 3, i.e. in traction and in compression,and

[0099] to link to the measured intensity a piece of information relatingto the direction of the force considered, and

[0100] in addition to the measured value of the induced force, to makeuse of the information relating to the direction of the induced force,both in calculating an average value and in monitoring the developmentof the force during an act of braking, so as to actuate the brakingregardless of the direction of displacement of the vehicles 1, 2connected through the coupling device 3 and regardless of theinclination of the surface on which said vehicles are moving.

[0101] In a manner likewise noteworthy, the controlling apparatus 73 isdesigned to ensure the following operations:

[0102] when the force induced in the coupling device 3 is detected inthe direction of compression of said coupling device 3,

[0103] increasing of the braking if, in absolute value, the difference Dbetween the measured intensity of the induced force and said targetvalue 10 is greater than a first predetermined threshold value A,

[0104] maintaining the braking in the same state if, in absolute value,the difference D between the measured intensity of the induced force andsaid target value 10 is less than said first predetermined thresholdvalue A,

[0105] when the force induced in the coupling device 3 is detected inthe direction of traction of said coupling device 3,

[0106] reducing the braking if, in absolute value, the difference Dbetween the measured intensity of the induced force and said targetvalue 10 is less than a second predetermined threshold value B,

[0107] maintaining the braking in the same state if, in absolute value,the difference D between the measured intensity of the induced force andsaid target value 10 is greater than said second predetermined thresholdvalue B, but less than a third predetermined threshold value C,

[0108] increasing the braking if, in absolute value, the difference Dbetween the measured intensity of the induced force and said targetvalue 10 is greater than said third predetermined threshold value C.

[0109] In a manner likewise noteworthy, the controlling apparatus 73 isdesigned to ensure the following operations:

[0110] monitoring and detecting the instant starting at which the towingvehicle 2 and the trailer vehicle 1 are able to roll.

[0111] In a likewise noteworthy and preferred manner, the controllingapparatus 73 is designed to ensure the following operations:

[0112] monitoring and detecting a switching on of voltage to a motormeans element 6 of the towing vehicle 2, i.e. an occurrence indicatingthe instant starting at which the towing vehicle 2 and the trailervehicle 1 are about to roll.

[0113] Finally, in a preferable, but non-limiting, way, the controllingdevice 73 is designed to ensure the following operations:

[0114] obtaining at the level of each wheel 4 of the trailer vehicle 1an indication relating to the rotation of that wheel 4, and

[0115] taking into account the indications about the rotation of each ofsaid wheels 4 of the trailer vehicle 1 so as to prevent their blockingin braking phase.

[0116] In a noteworthy manner, the controlling apparatus 73 is designedto monitor a switching off of voltage to a motor means element 6 of thetowing vehicle 2 and when such a switching off is detected to actuatethe braking device 3 of the trailer vehicle 1 so as to stop said trailervehicle 1.

[0117] These features make it possible to ensure the stopping of thetrailer vehicle in the event of failure of the coupling device, forexample in the case of breakage.

[0118] In a likewise noteworthy way, the force sensor 30 is disposed ina part of the coupling device connected to the trailer vehicle 1.

[0119] One of the interesting aspects of the device according to theinvention is that it does not require any special installation on thetowing vehicle.

[0120] The method implemented in this device ensures its automaticcalibration as a function of the load of the trailer vehicle and thisthrough the indirect means of the regulation of the braking.

[0121] With this method implemented in the device according to theinvention, the trailer vehicle is no longer braked inopportunely and thebraking is also ensured and regulated when the trailer vehicle isbacking up.

[0122] Finally, the method according to the invention is compatible withthe use of a “retarder” device.

[0123] The control device according to the invention is particularlyadvantageous because it can be placed entirely on the trailer vehicle,and a trailer vehicle can thus be obtained which is compatible with anytowing vehicle under the condition that this towing vehicle delivers asignal of operation of its braking device, which is the case, forexample, with an electrical connecting device between vehiclesimplementing a thirteen pole connector of standardized type known underthe reference ISO 11446.

1. A method for controlling a braking device equipping a first rollingvehicle, referred to as the trailer vehicle, connected through acoupling device to a second vehicle, referred to as the towing vehicle,the towing vehicle being itself equipped with a braking device providedwith an actuation element, according to which method, when braking thetowing vehicle: the intensity of the force induced in the couplingdevice is measured, at least at a given instant, then the measuredintensity of the induced force at the given instant under considerationis compared with a target value determined beforehand and, when thedifference between the measured intensity of the induced force and saidtarget value deviates from a predetermined tolerated threshold, theactuation of braking elements of the trailer vehicle is initiated toinfluence the braking of said trailer vehicle, and the aforementionedsteps are repeated of measuring, comparing, and initiating the brakinguntil the difference between the measured intensity of the induced forceand the target value is less than the predetermined tolerated threshold,wherein through monitoring, the instant starting from which the towingvehicle and the trailer vehicle are about to roll is detected, then,starting from that instant at least in an intermittent way, theintensity of the force induced in the coupling device is measured and,for a period of measurement of predetermined duration, the average valueis calculated of the intensity of the induced force and this averagevalue is stored, after completion of the storage of an average value,the steps are repeated of measuring, calculating a new average valuethen of storing this new average value, replacing the average valuepreviously stored, with a view to initiating the actuation of thebraking elements of the trailer vehicle at any chosen instant after thecalculation of an average value, taken as the target value is theaverage value of the intensity of the induced force which has beencalculated in the period of measurement preceding the instant chosen toinitiate said braking.
 2. The method according to claim 1, wherein toinitiate the actuation of the braking elements of the trailer vehicle atany chosen instant after the calculation of an average value: theproduction is monitored on the towing vehicle of a signal, referred toas the operational signal, which indicates the actuation of its brakingdevice and thus the instant chosen to initiate the braking of thevehicles, and when the force induced in the coupling device 3 by thetrailer vehicle 1 deviates with respect to the tolerated thresholdpredetermined with respect to the target value, the actuation of thebraking elements of the trailer vehicle is initiated, with a view tocorrecting the intensity of said induced force, only if the signal ofoperation of the braking device of the towing vehicle has been detectedbeforehand.
 3. The method according to claim 1, wherein the productionis monitored on the towing vehicle of a signal which, referred to as theoperational signal, is an electrical signal produced to activate theoperation of luminous signals intended to indicate the use of the brakesof said towing vehicle, and thus indicate the actuation of the brakingdevice of this vehicle.
 4. The method according to claim 2, wherein theproduction is monitored on the towing vehicle of a signal which,referred to as the operational signal, is an electrical signal producedto activate the operation of luminous signals intended to indicate theuse of the brakes of said towing vehicle, and thus indicate theactuation of the braking device of this vehicle.
 5. The method accordingto claim 2, wherein, when the actuation of the braking is detected, theprocess of calculation of an average value for the force induced in thecoupling device is interrupted, and the development of the force inducedin the coupling device is monitored and, when the braking has beenachieved, the process of calculation of the average value for the forceinduced in the coupling device is resumed.
 6. The method according toclaim 1, wherein the intensity of the force induced in the couplingdevice is measured with a predetermined frequency of measurement so asto achieve a substantially continuous monitoring of the intensity of theforce induced in said coupling device.
 7. The method according to claim1, wherein: the intensity of the force induced in the coupling device bythe trailer vehicle is measured in the two possible directions of stressof the coupling device, i.e. in traction and in compression, and a pieceof information relating to the direction of the force considered islinked to the measured intensity, and used in addition to the measuredvalue of the induced force both in calculating an average value and inmonitoring the development of the force during an act of braking is theinformation relating to the direction of the induced force so as toactuate the braking regardless of the direction of displacement of thevehicles connected through the coupling device and regardless of theinclination of the surface on which said vehicles are moving.
 8. Themethod according to claim 7, wherein: when the force induced in thecoupling device is detected in the direction of compression of saidcoupling device, if, in absolute value, the difference between themeasured intensity of the induced force and said target value is greaterthan a first predetermined threshold value, then the braking isincreased, whereas if, in absolute value, the difference between themeasured intensity of the induced force and said target value is lessthan said first predetermined threshold value, then the braking ismaintained in the same state, when the force induced in the couplingdevice is detected in the direction of traction of said coupling device,if, in absolute value, the difference between the measured intensity ofthe induced force and said target value is less than a secondpredetermined threshold value, then the braking is decreased, if, inabsolute value, the difference between the measured intensity of theinduced force and said target value is greater than said secondpredetermined threshold value, but less than a third predeterminedthreshold value, then the braking is maintained in the same state, if,in absolute value, the difference between the measured intensity of theinduced force and said target value is greater than said thirdpredetermined threshold value, then the braking is increased.
 9. Themethod according to claim 1, wherein to detect the instant starting atwhich the towing vehicle and the trailer vehicle are about to roll, theswitching on of voltage to a motor means element of the towing vehicleis monitored.
 10. The method according to claim 1, wherein, for controlof the braking device of the trailer vehicle, an indication is obtainedat the level of each wheel of the trailer vehicle relating to therotation of that wheel, and the indications about the rotation of eachof said wheels of the trailer vehicle are taken into account so as toprevent their blockage in braking phase.
 11. The method according to oneof the claims 1 to 10, wherein a switching off of voltage to a motormeans element of the towing vehicle is monitored and when such aswitching off of voltage is detected, the braking device of the trailervehicle is actuated so as to stop said trailer vehicle.
 12. A brakingdevice for a trailer vehicle intended to be connected to a towingvehicle through a coupling device, wherein this braking device comprisesat least one controlling apparatus ensuring the following operations: tomonitor and detect the instant starting at which the towing vehicle andthe trailer vehicle are about to roll, and starting at that instant, atleast intermittently, to measure the intensity of the force induced inthe coupling device, and for a measuring period of predeterminedduration, to calculate the average value of the intensity of the inducedforce and to store that average value, upon completion of storing anaverage value, to repeat the steps of measuring, of calculating a newaverage value, then of storing this new average value replacing theaverage value previously stored, with a view to initiating the actuationof the braking elements of the trailer vehicle at any chosen instantafter calculation of an average value, to take as a target value theaverage value of the intensity of the induced force which has beencalculated in the measurement period preceding the instant chosen foractuating said braking.
 13. The device according to claim 12, whereinthe controlling apparatus is designed: to monitor and detect theproduction of a signal of operation of an actuation element for abraking device of a towing vehicle, this signal making known the instantchosen for actuation of the braking, when such an operational signal hasbeen detected, to determine whether the intensity of the force inducedin the coupling device by the trailer vehicle deviates from a toleratedthreshold predetermined with respect to a previously stored targetvalue, to initiate the actuation of the braking elements of the trailervehicle in the case where the intensity of the force induced in thecoupling device by the trailer vehicle deviates from a toleratedthreshold predetermined with respect to the target value.
 14. The deviceaccording to claim 12, wherein the controlling apparatus is designed tomonitor the production on the towing vehicle of a signal which, referredto as the operational signal, is an electrical signal produced toactivate the operation of luminous signals intended to indicate the useof the brakes of said towing vehicle, and thus make known the actuationof the braking device of this vehicle.
 15. The device according to claim13, wherein the controlling apparatus is designed to monitor theproduction on the towing vehicle of a signal which, referred to as theoperational signal, is an electrical signal produced to activate theoperation of luminous signals intended to indicate the use of the brakesof said towing vehicle, and thus make known the actuation of the brakingdevice of this vehicle.
 16. The device according to claim 13, whereinthe controlling apparatus is designed to interrupt, when the actuationof the braking is detected, the process of calculation of an averagevalue for the force induced in the coupling device and to monitor thedevelopment of the force induced in said coupling device, and, when thebraking has been achieved, to resume the process of calculation of theaverage value for the force induced in the coupling device.
 17. Thedevice according to claim 12, wherein the controlling apparatus isdesigned to measure the intensity of the force induced in the couplingdevice with a predetermined frequency of measurement so as to achieve asubstantially continuous monitoring of the intensity of the forceinduced in said coupling device.
 18. The device according to claim 12,wherein the controlling apparatus is designed: to measure the intensityof the force induced in the coupling device by the trailer vehicle inthe two possible directions of stress of this coupling device, i.e. intraction and in compression, and to link to the measured intensity apiece of information relating to the direction of the force considered,and in addition to the measured value of the induced force, to make useof the information relating to the direction of the induced force, bothin calculating an average value and in monitoring the development of theforce during an act of braking, so as to actuate the braking regardlessof the direction of displacement of the vehicles connected through thecoupling device and regardless of the inclination of the surface onwhich said vehicles are moving.
 19. The device according to claim 18,wherein the controlling apparatus is designed: when the force induced inthe coupling device is detected in the direction of compression of saidcoupling device, to increase the braking if, in absolute value, thedifference between the measured intensity of the induced force and saidtarget value is greater than a first predetermined threshold value, tomaintain the braking in the same state if, in absolute value, thedifference between the measured intensity of the induced force and saidtarget value is less than said first predetermined threshold value, whenthe force induced in the coupling device is detected in the direction oftraction of said coupling device, to reduce the braking if, in absolutevalue, the difference between the measured intensity of the inducedforce and said target value is less than a second predeterminedthreshold value, to maintain the braking in the same state if, inabsolute value, the difference between the measured intensity of theinduced force and said target value is greater than said secondpredetermined threshold value, but less than a third predeterminedthreshold value, to increase the braking if, in absolute value, thedifference between the measured intensity of the induced force and saidtarget value is greater than said third predetermined threshold value.20. The device according to claim 12, wherein the controlling apparatusis designed to monitor and detect the instant starting at which thetowing vehicle and the trailer vehicle are about to roll.
 21. The deviceaccording to claim 12, wherein the controlling apparatus is designed tomonitor and detect a switching on of voltage to a motor means element ofthe towing vehicle, i.e. an occurrence indicating the instant startingat which the towing vehicle and the trailer vehicle are about to roll.22. The device according to claim 12, wherein the controlling apparatusis designed: to obtain at the level of each wheel of the trailer vehiclean indication relating to the rotation of that wheel, and to take intoaccount the indications about the rotation of each of said wheels of thetrailer vehicle so as to prevent their blocking in braking phase. 23.The device according to claim 12, wherein the controlling apparatus isdesigned to monitor a switching off of voltage to a motor means elementof the towing vehicle and when such a switching off is detected toactuate the braking device of the trailer vehicle so as to stop saidtrailer vehicle.
 24. The device according to one of the claims 12 to 23,wherein, to ensure the operation of monitoring and detecting, saidcontrolling apparatus comprises a force sensor disposed in a part of thecoupling device connected to the trailer vehicle.